Mono project brings .NET to Linux
 

Mono, a three year effort, is an open source project that ports the underlying core .NET technology to Linux. The c #programming language pre written code libraries and Microsoft's common language runtime are being written into the project.
Mono, which is not a development tool like visual studio .NET, will make it easier for windows programmers to write applications for linux. Mono also supports Mac OS.
More information about the project can be had from :Mono Project